Process of making unsaturated acyl cellulose esters



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This'invention relates to a simplified process of makin cellulose esters containing un-= saturated acy grou s. Que object of our'invention is to provi e a relatively simple and inexpensive; process of producing cellulose esters containing an acyljgroup corresponding to a monocarboxylic unsaturated organic acid in which there is an ethylenic bond. Another object of the invention is to provide m suclli a processin which the introduction of an acy acrylic acid series is introducedby a simple single step. Another object-of the invention is to provide a pmcessin which the introduction of the unsaturated acid to the ester is carried out first, and then other acyl groups of the ester may be subsequently introduced. Gther objects will hereinafter appear. 7

' We have found that cellulose esters containin small but useful amounts of unsaturate acyl groups may be prepared by simpl heating cellulose, either native or in a sh tly hydrated form, in a bath containing unsaturated acid and a solvent which lowers the boiling point of the mixture below a temperature at which harmful de radation oithe cellulose occurs. We have a so found that these lower esters of cellulose containing unsaturated acyl groups, are. very readily 3Q esterified further by the known methods of introducing saturated groups, such as those corresponding to the fatty acids. It will thus be seen that we have provided a very simple single-stage method of producing cellulose esters containing useful amounts of unsaturated acyl groups, and a relatively simple two-stage process in which such lower esters are first formed and then further esterifica-- group from a lower member of the part OFFICE a i. mania, or nocnus'rnn, 'NEW YORK, assremons 'ro nasr un xonax comm, or nocnmrnn, new YORK, A conrona'rron or NEW e mssa'rum'rnn AGYL cnnnunosn nsrmas Epplleaflcn area ma 4, 192?. Serial Ho. 188,861..

venience in this particular application, we shall refer to all such forms of cellulose as partially hydrated.

Weshall now describe several forms of our invention by way of illustration, but it will be understood that our invention is not restricted to the details thus given, except as indicated in the appended claims. 20 parts by weight of rayon fibers from the cuprammonium process are placed in a mixture of 300 parts by weight of crotonic acid and 50 parts by weight of chlorobenzene, and the mixture heatedfor 48 hours at 155 to 157 C. The presence of the chlorobenzene lowers the boilingpoint and gives a good liquid bath at these temperatures which are reasonably safe with respect to the cellulose and the esters which are formed therefrom. In general we preferably work at least below 170 C. Occasionally the moisture is removed by distilling off chlorobenzeneand replacing it with the same amount of dry chlorobenzene. The fibers now consist, not of plain reverted cellulose, but of lower cellulose crotonate esters. Such fibers are useful by themselvesin this condition, because the unsaturated acyl groups in them ofier points at which chemical modifications or substitutions may be made, thus providing for special'dyeing treatment, for example. They contain 4.8% by wei ht of crotonyl grou s.

The ower crotonates descri ed in the pre ceding paragraph may be further esterified in any of the usual ways. If an. aceto-crotonate 'is to be produced, they may be added to a regular acetylating mixture, such as one cont'ainin 30 parts by weight of acetic acid, 20 parts y weight of acetic anhydrid, and. l ,b weight of fused or anhydrous zinc chloridi Into this bath 5 parts by weight of the above described lower crotonates are stirred and the mixture warmed at to C. until a homogeneous dope is obtained. From this dope the cellulose aceto-crotonates are recipitated by means of water, and the pro uct washed and dried. It is soluble in chloroform, or acetone, or mixtures of them and ields transparent colloidized films upon the rying of its solutions.

In another form of our invention long boiling mixture of 500 parts by weight of .crotonic 'acid and 100 parts by weight of -fibe redfcotton is merceriz ed for 48 hours in an 18% sodium hydroxide solution, pressed out, washed free ofalkali, and then freed fromwater by washing with alcohol and ether, finally being dried. r The combination of the'mercerizing; action and the special dehydratin leaves the fibers with the surface iin a specia y good condition for-further reweight of the mercerized action; '20 parts by fi ers are then heated in a and dehydrated chlorobenzene. The temperature remams at 155 to 157 C. Chlorobenzene is a good'example of an inert liquid which lowers the boiling point to a degree where the temperature is safefor the reaction and the products. Thewater liberated by the reaction is periodically removed b distillation, the chlorobeniene which distil ls out being replaced with dry chlorobenzene. After 48 hours treatment, there is approximately 4.9% by weight of crotonyl groups combined with the cellulose', and after 96 hours treatment there is. about 6.7% of crotonyl groups in the lower esters thus produced. Where native cellulose, such as clean cellulose fibers or paper as used in manufacturing cellulose acetate, is substi- The additional acyl groups may be a any tuted for the mercerized cellulose in the above example, the amount of crotonic groups introduced by the boiling is about one-fourth the amountintroduced into the mercerized cellulose foran equal time of treatment.

The resulting fibers are useful, by themselves, after washin and drying, because of.

the chemical operatlons which maybe carried out with respect to them by reason of the double bond in the crotonic groups. But

these esters are likewise well adapted for the fibers are introduced mto 15.parts by weight of acetic anhydrid, and 20 parts-by weight of acetic-acid, along with 0.1 part by weight of magnesium perchlorate. The reaction is conducted at to 0., the end point being obtained b indicated by the mass becoming homogeneous. From this mass the aceto-crotonates are precipitation with .Water or methyl alco '01, and washedby means of the latter. The product is soluble in acetone or chloroform'or mixtures of them and yields transparent films from the evaporation of its solutions.

. Stearyl groups may be introduced into the lower crotonates ,hereinabove described, as follows: 4 parts by weight of thelower cellulose crotonate fibers are mixed into 30 parts 65 by weight of commercial stearic acid,'50 parts by weight of chloroacetic anhydrid, and 0.1 part by weight of magnesium perchlorate. The mixture is kept at 60 to 65 C. until a homogeneous solution or dope is obtained, say in about 20 hours.. The resulting dope is poured into methyl alcohol, and the precipitated cellulose crotono-stearate (or steamcrotonate) is washed with warm methyl alcohol and dried. It is soluble in chloroform and benzol, and yields flexible, transparent skins uponevaporation of its solutions.

Of the other members of the acrylic series of unsaturated acids undecylenic maybe used alongwith a solvent which reduces its boiling point sufficiently, but in general, we prefer to use crotonic acid, because of its lower boiling point and greater activity. Cinnamica'cid' is likewise useful.

The lower esters containing unsaturated acyl groups introduced by our simplified heating step may be further esterified, not only with acetyl groups or'stearyl groups, as explained in the above illustrations, but with any of the groups introduced by the methods disclosed in our copending application Serial N 0.17 9,177 filed March 28th, 1927, for

Process of making cellulose esters of organic acids. In said application cellulose esters are prepared by using one or more of the group of carboxy-lic acids contained in the subgroups. consisting ofthe unsubstituted ahphat1c monocarboxylic acids including the cycloparaflinic, the aromatic monocarboxylic acids and the aralkyl monocarbox 'lic acids, t ical members of these carboxy '0 groups bemgfthe following: acetic, proplonic, n-butyric, iso-butyric, n-valeric, iso-valeric, n-caproic, n-heptylic, ca ligllic, pelargonic, capr 1c, lauric, myristic, pa 'tic, steanc, crotonic, cyclohexane-carbox lic, benzoic, omethoxy-benzoic, o-chloroenzoic, acetylsalicylic, phenylacet ic, hydrocinnamic and cin-.

namic. The acid with which the cellulose is to be esterfied is mixed with the cellulosic material and a catalyst in the presence of an erable to further esterify with one 0 the other acids mentioned.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In the process of making organic esters of cellulose, heating together a cellulose and a monocarboxylic or anic acid in which there is. an ethylenic bon until a lower cellulose ester containing an unsaturated acyl group is produced, the temperature of the in redients being maintained below the degradation points of the cellulose and the ester.

2. In the process of making organic esters of cellulose, boiling partially hydrated cellulose in a bath containing a monocarboxylic organic acid in which there is an ethylenic bond and a liquid miscible with said acid which is inert toward the cellulose and pro duces with the acid a mixture boiling below the degradation point of the cellulose, said boiling being continued until a lower cellulose ester containing an unsaturated acyl group is roduced.

3. In t e process of making organic esters of cellulose, heating together partially hydrated cellulose and crotonic acid, until a lower cellulose crotonate is produced, the temperature of the ingredients being maintained below the degradation points of the cellulose and the cellulose crotonate.

4. In the process of making organic esters drated cellulose in a bath of crotonic acid and chlorobenzol until a lower cellulose crotonate is produced, and thereafter further esterifying said lower crotonate in an esterifying bath containing acetic anhydrid.

Signed at Rochester, New York, this 29th day of April, 1927.

HANS T. CLARKE. CARL J. MALM.

of cellulose, boiling partially hydrated cellulose in a bath containing cfotonic acid and a solvent thereof which is inert toward the cellulose and produces with the acid a mixture boiling below the degradation point of the cellulose, said boiling being continued until a lower cellulose crotonate is produced.

5. In the process of making organic esters of cellulose, boiling mercerized cellulose in a bath containing crotonic acid and chloroben-' zol, at a temperature between 155 and 160 C. for at'least 48 hours, and thereafter separating the lower .cellulose crotonate, thus formed, from the reaction mixture.

6. In the process of making organic esters of cellulose, heating together partially hydrated cellulose and a monocarboxyhc organic acid in which there is an ethylenic bond until a lower cellulose ester containing an unsaturated acyl group is produced, and thereafter further esteri ying said lower cellulose ester.

7. In the rocess of makin organic esters of cellulose, iling partially ydrated cellulose in a bath containing a monocarboxylic organic acid in which there is an ethylenic bond and a liquid miscible with said acid which is inert toward the cellulose and'produces with the acid a mixture boiling below the boiling points of either said acid or said liquid, said boiling being continued until a lower cellulose ester containing' an unsaturated acyl group is produced, and thereafter further esterifying said lower ester in an anhydrid bath containing reactive fatty acid groups. 7/

8. In the rocess of makin organic esters of cellulose, iling partiallyiydrated cellulose in a bath containing crotonic acid and a liquid which is inert toward the cellulose and 

